YWIW,
You're right, flying is supposed to be fun, and if you're not enjoying it, something is wrong.
Take a step back, and think about what you're doing. Do you actually not enjoy flying? Do you really believe that an engine fire is sufficiently likely that it's causing you anxiety?
I think you'll find the answer to both questions is No. I believe your problem is that you're trying to get a PPL. IMHO, that's not the correct way of going about it. What I think you should be doing is trying to enjoy yourself for an hour a week.
What that means is book an aeroplane each weekend, and keep your fingers crossed. Some weekends you'll go flying, some weekends you won't. That's life - it won't be any different after you get your PPL, so why should you expect it to be different now?
"But that will mean it takes ages to get my PPL." Yes. So what? If the aim is to enjoy yourself for an hour each week (weather permitting), then you're acheiving your aim, even if it takes 12 months or more to get your PPL.
And once you've got the PPL, nothing will really change. You'll still book the aircraft each weekend (you'll probably have progressed from one hour flights to two hour flights by then) You'll head down to the airfield and go flying. You can take your choice of passenger with you, and you can go where you want instead of where your instructor tells you to go, but that's about the only difference.
Stop spending all weekend at the airfield. Stop taking weeks off work, because if the weather is bad you'll regret it. Book your slot, and if the weather's no good, try again next weekend. If the weather's good, excellent, you can spend another hour doing one of the most amazing things that Mrs YWIW will ever let you do without her!
(Also, bear in mind that learning to land is not easy. You will be disappointed, and it's very easy to just give up. Things do start to become more interesting again soon, especially when you get close to solo - but in the mean time, every time you park, think about what you enjoyed about the flight. "Hey, the vis was amazing today, I could almost see the coast!" "Hey, that third landing I did today was perfect!" "What d'you know, I actually did all the run-up checks without my instructor commenting on the fact that I'd missed something today!" This will help you enjoy the least enjoyable part of learning to fly.)
But above all - make sure you have fun!
Take care, but don't thow in the towel just yet - at least, not without thinking it through rationally first.
FFF
-----------